Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h,w = map(int, input().split())
s = [list('#'+input()+'#') for i in range(h)]
s = [['#']*(w+2)]+s+[['#']*(w+2)]
z=0
for i in s:
  z += i.count('.')
ans = [[-1]*(w+2) for i in range(h+2)]
m = [[0,1],[0,-1],[1,0],[-1,0]]
ans[1][1] = 1
d = deque([[1,1]])
while len(d):
  x,y = d.popleft()
  for i,j in m:
    a,b = x+i,y+j
    if s[a][b] == '.' and ans[a][b] == -1:
      d.append([a,b])
      ans[a][b] = ans[x][y]+1
if ans[h][w] == -1:
  print(-1)
else:
  print(z-ans[h][w])